Motors disclosed in the International Publication Nos. PCT01/37402 and PCT01/37409 are known as conventional motors, particularly motors used in an EGR-V.
However, in such conventional motors, an upper face of a stator is formed into an approximately flat surface. Therefore, there is a possibility that powder produced by abrasion at a brush falls on the upper face of the stator, gradually moves inside, and enters from a motor shaft part into the motor (especially into a bearing holding portion of the stator). This eventually results in increase in sliding resistance of a rotor.
In order to secure air-tightness in lower part of the stator, any fluid sealant is sandwiched between the stator and the boss at a space formed between the stator portion and a boss portion fitted thereinto. However, the face to which the fluid sealant is applied is flat, and this brings about a disadvantage that a joint gap is formed due to irregular configuration in the flat surface and a minute change in configuration after continuous operation, thereby losing air-tightness.
The position sensor portion is fixed to the stator portion by welding (hot wire method). In this hot wire method, two parts (in this case, the position sensor portion and the stator portion) forming a nested structure (rough portion to be welded) are joined together by application of a current to a wire set between the two parts. Thus, a heat is generated and a resin is fused (see the Japanese Patent Publication (unexamined) No. 2000-006247).
Such a conventional art, however, has a disadvantage that the resin overflows at the time of welding due to dimensional irregularity in the rough portion to be welded, and leakage (poor air-tightness) occurs in the space between butt parts depending upon the manner the wire is set.
Moreover, in the conventional motor, a coil is wound and ended at the base portion of a terminal led from a stator core. In the case where the terminal and the winding (coil) are joined together by soldering, it is essential to soak the whole terminal in solder, and as a result, the whole terminal is unnecessarily soldered. This causes a disadvantage that the-solder flows out of a portion molded in a mold at the time of molding the stator core, and the soldering is carried out while shaving off the solder sticking to the terminal. Consequently, a problem exists in that solder shavings are accumulated in the mold and are mixed with the resin.
As discussed above, in the conventional motor, a problem exists in that powder is produced by abrasion at the brush, and enters into the motor, thereby increasing the sliding resistance of the rotor.
Another problem exists in that a joint gap occurs due to irregular configurations of the flat surface part at the space between the stator portion and the boss portion fitted into the stator portion and to a minute change in configuration after a continuous operation, eventually resulting in losing air-tightness.
A further problem exists in that, at the time of welding the position sensor portion and the stator portion together by hot wire method, the resin overflows due to dimensional irregularity of the welded portion. Thus, leakage (poor air-tightness) occurs at the gap between butt parts depending upon the manner of setting the wire.
A still further problem exists in that the soldering is carried out while shaving off the solder sticking to the terminal and, as a result, solder shavings are accumulated in the mold and are mixed with the resin.
The present invention has an object of providing a motor capable of preventing powder produced by abrasion at a brush from entering in the motor.
The invention has another object of providing a motor capable of improving air-tightness in a space between a stator portion and a boss portion fitted into the stator portion.
The invention has a further object of providing a motor capable of preventing leakage of resin at a portion where the position sensor portion and the stator portion are welded together.
The invention has a yet further object of providing a motor capable of preventing solder shavings accumulating in the mold at the time of molding the stator core.